Thorne was last seen in Brea, California on January 13, 1998. His friends claimed they dropped him off near his home in the evening, after a school field trip. He never arrived home and has never been heard from again. His mother filed a missing persons report the next day.

In 2004, five witnesses came forward and admitted they lied about dropping Thorne off safely the evening of his disappearance, and stated that Robert Anthony Marquez killed him and then told the witnesses to tell investigators the false story. They had not told earlier because they were afraid Marquez would murder them too. One of Thorne's friends became worried when he found out that Marquez was about to be released from prison for an unrelated extortion offense, and went to police with this story. The four other youths, one of whom is Marquez's girlfriend and the mother of his son, backed the first one up.

A photograph of Marquez is posted below this case summary. He claims to be a Satanist and police believe Thorne's murder may have been part of a Satanic ritual. When police spoke to Marquez in prison, he admitted to involvement in Thorne's death. He stated that Thorne accepted a ride to a movie theater with Marquez, whom he didn't know, and went to Marquez's grandparents' house afterwards with his friends. They smoked marijuana and afterwards, Marquez stabbed Thorne in the throat with a knife. Thorne's body was reportedly dismembered and put in a dumpster behind a Lucky's supermarket; it has not been found.

Marquez has a history of violence against teenage boys; he reportedly tried to strangle a thirteen-year-old boy in 1998, the same year Thorne disappeared. He was convicted of murdering Thorne in 2005 and was sentenced to 51 years to life in prison. Prosecutors are not sure why he killed Thorne.

Thorne's mother describes him as an avid golfer. He was a student at Brea Canyon High School at the time of his disappearance. Foul play is suspected in his case due to the circumstances involved.

Investigating Agency If you have any information concerning this case, please contact: Brea Police Department